It depends on what you mean. If you're talking about which one had better songs, I'd have to say it's a tie. They both had some brilliant songwriting and talented vocalists, so it's difficult to choose one over the other. But I went with Once More, With Feeling because the plot is better (not to mention the fact that they managed to make just as much, if not more development in an episode filled with songs as they do in a regular season-wide arc episode, which is VERY rare) and we had already grown to know and love the characters. Also, Joss didn't hire the actors in Buffy based on their musical ability, whereas in Dr. Horrible, he hired people that he knew could act and sing pretty well.